CN100573877C - Static random access memory and manufacture method thereof - Google Patents

Static random access memory and manufacture method thereof Download PDF

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Publication number
CN100573877C
CN100573877C CNB200610170188XA CN200610170188A CN100573877C CN 100573877 C CN100573877 C CN 100573877C CN B200610170188X A CNB200610170188X A CN B200610170188XA CN 200610170188 A CN200610170188 A CN 200610170188A CN 100573877 C CN100573877 C CN 100573877C
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China
Prior art keywords
potential layer
transistor
random access
power supply
access memory
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Expired - Fee Related
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CNB200610170188XA
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CN1992281A (en
Inventor
朴盛羲
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DB HiTek Co Ltd
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Dongbu Electronics Co Ltd
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B99/00—Subject matter not provided for in other groups of this subclass
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B10/00—Static random access memory [SRAM] devices
    • H10B10/12—Static random access memory [SRAM] devices comprising a MOSFET load element
    • H10B10/125—Static random access memory [SRAM] devices comprising a MOSFET load element the MOSFET being a thin film transistor [TFT]
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B10/00—Static random access memory [SRAM] devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S257/00—Active solid-state devices, e.g. transistors, solid-state diodes
    • Y10S257/903—FET configuration adapted for use as static memory cell

Abstract

The invention discloses a kind of static random access memory (SRAM), it comprises: by first access transistor and second access transistor of metal-oxide semiconductor (MOS) (MOS) transistor formation; First driving transistors and second driving transistors by metal-oxide semiconductor (MOS) (MOS) transistor formation; And the p-channel thin-film transistor (TFT) and the 2nd p-channel thin-film transistor that are used as the pull-up device use.This SRAM comprises: the earth potential layer, and it is provided as the common-source of this first driving transistors and this second driving transistors, and forms by dopant is injected Semiconductor substrate; The power supply potential layer, its source electrode with a p-channel TFT and the 2nd p-channel TFT is connected; And insulating barrier, its be formed on this substrate and place this earth potential layer and this power supply potential layer between.

Description

Static random access memory and manufacture method thereof
Technical field
The method that the present invention relates to a kind of static random access memory (Random Access Memory is hereinafter to be referred as SRAM) and make this memory.
Background technology
Static random access memory (SRAM) is that a kind of mode (latch manner) that latchs of can using is stored the memory of data part in circuit.This SRAM device speed of service is high and low in energy consumption, and with dynamic random access memory (dynamic random access memory is called for short DRAM) difference, it does not need regular update institute canned data.
Usually, SRAM comprises two drop-down (pull-down) devices, two accesses (access) device, and draw (pull-up) device on two, this SRAM is divided into three types according to the structure of pull-down: full complementary metal oxide semiconductors (CMOS) (Complementary Metal-Oxide Semiconductor, abbreviation CMOS) type, high capacity resistor (high load resistor, be called for short HLR) type and thin-film transistor (thin film transistor is called for short TFT) type.The SRAM of whole CMOS type uses p-channel body mos field effect transistor (MOSFET) as pull-down.HLR type SRAM uses has the polysilicon layer of high electrical resistance value as pull-up device.The SRAM of TFT type uses p-raceway groove multi-crystal TFT as pull-up device.At this, the SRAM of TFT type can reduce the size of unit significantly, therefore makes things convenient for it to be used for the semiconductor storage unit that only uses as memory device.
SRAM has multiple structure, and wherein the most frequently used is to comprise 6 transistorized whole CMOS type SRAM.And whole CMOS type SRAM uses the p-channel TFT to increase the integrated level of memory cell because of its bigger area.Yet because power supply potential layer Vcc's is high resistive, the whole CMOS type SRAM speed of service is lower.
Summary of the invention
Therefore, the present invention relates to the structure of a kind of SRAM, wherein can further improve driving force.
The method that the purpose of this invention is to provide a kind of SRAM of manufacturing, wherein power supply potential layer (powersupply potential layer) closely equipotential layer (ground potential layer) be provided with improving the speed of service of this SRAM, and can avoid the latch phenomenon that between this power supply potential layer and this earth potential layer, occurs effectively.
According to a scheme of the present invention, the invention provides a kind of static random access memory (SRAM), it comprises: by first access transistor and second access transistor of metal-oxide semiconductor (MOS) (MOS) transistor formation; First driving transistors and second driving transistors that constitute by metal oxide semiconductor transistor; And the first and second p-channel thin-film transistors (TFTs) that are used as pull-up device.This SRAM comprises: the earth potential layer, and it is as the common-source setting of this first driving transistors and this second driving transistors, and forms by dopant is injected Semiconductor substrate; Power supply potential layer, its source electrode with a p-channel TFT and the 2nd p-channel TFT are connected and are provided with near this earth potential layer; And insulating barrier, its be formed on this substrate and place this earth potential layer and this power supply potential layer between.
According to another scheme of the present invention, the invention provides the method for a kind of SRAM of manufacturing, wherein this SRAM comprises: by first access transistor and second access transistor of metal-oxide semiconductor (MOS) (MOS) transistor formation; First driving transistors and second driving transistors that constitute by metal oxide semiconductor transistor; And the p-channel thin-film transistor (TFT) and the 2nd p-channel thin-film transistor that are used as pull-up device.This method may further comprise the steps: form the photoresist pattern that exposes active area of semiconductor substrate; Dopant is injected the part that this active area is exposed by this photoresist pattern, and form the earth potential layer thus; Remove this photoresist pattern; On this earth potential layer, form insulating barrier; And on this insulating barrier, form the power supply potential layer.
Description of drawings
Fig. 1 is the circuit diagram that the static random access memory (SRAM) according to the embodiment of the invention is shown;
Fig. 2 A illustrates the layout of SRAM according to an embodiment of the invention, and Fig. 2 B is the sectional view that dissects along the line A-A among Fig. 2 A; And
Fig. 3 A, Fig. 3 B are to be used for explaining according to the sectional view of embodiments of the invention in the method for SRAM parallel formation power supply potential layer and earth potential layer with Fig. 3 C.
Embodiment
Below, will describe in conjunction with the accompanying drawings according to a kind of static random access memory (SRAM) of the embodiment of the invention and the method for making this memory.
In following explanation to embodiments of the invention, when one deck was formed on the another layer, it can directly be formed on another layer, maybe one or more insert layers can occur.
Fig. 1 is the circuit diagram that the static random access memory (SRAM) according to the embodiment of the invention is shown.At this, the PMOS transistor uses for example as resistance device.And Fig. 2 A is the layout that illustrates according to the SRAM of the embodiment of the invention, and Fig. 2 B is the sectional view that the line A-A along Fig. 2 A dissects.
With reference to Fig. 1, sram cell comprises: first access nmos pass transistor (TFT) Ta1 and second access nmos pass transistor (TFT) Ta2, and described transistor is connected bit line BL and bit line bar 1BL by the first node N1 of memory cell with Section Point N2; The one p-channel thin-film transistor Tf1 and the 2nd p-channel thin-film transistor Tf2, described TFT are connected between power supply potential layer Vcc and node N1 and the node N2; And first the driving N MOS transistor Td1 and the second driving N MOS transistor Td2, described transistor is connected between node N1 and node N2 and the earth potential layer Vss.
At this, a p-channel thin-film transistor Tf1 and the first driving N MOS transistor Td1 thus, provide the voltage of power supply potential layer Vcc or earth potential layer Vss by the signal controlling of Section Point N2 to first node N1.Equally, the 2nd p-channel thin-film transistor Tf2 and the second driving N MOS transistor Td2 thus, provide the voltage of power supply potential layer Vcc or earth potential layer Vss by the signal controlling of first node N1 to Section Point N2.As the first access nmos pass transistor Ta1 of access device, as the first driving N MOS transistor Td1 of pull-down and as the joint of a p-channel thin-film transistor Tf1 of pull-up device first node N1 for the storage data, and the second access nmos pass transistor Ta2, the second driving N MOS transistor Td2, and another point that the 2nd p-channel thin-film transistor Tf2 crosses is for storing the Section Point N2 of data.
With reference to Fig. 2 A and Fig. 2 B, n-N-type semiconductor N substrate 100 has: trap 101 wherein is injected with the dopant (for example, p-type dopant) of opposite conductivity types; And active area 102, it limits by separator.The grid 120 of the grid 110 of the first access nmos pass transistor Ta1 and the second access nmos pass transistor Ta2 is connected to word line WL.Source electrode 112s by injecting the first access nmos pass transistor Ta1 that n-type dopant forms and the source electrode 122s of the second access nmos pass transistor Ta2 are connected to bit line BL and bit line bar 1BL by contact site 114 and 124 respectively.
Simultaneously, drain electrode 112d by injecting the first access nmos pass transistor Ta1 that n-type dopant forms and the drain electrode 132d of the first driving N MOS transistor Td1, be connected with the drain electrode 152d of a p-channel thin-film transistor Tf1 who forms by injection p-type dopant, and be connected with 180c by contact site 180a, 180b with the grid 140 of the second driving N MOS transistor Td2 and the grid 160 of the 2nd p-channel thin-film transistor Tf2.Equally, drain electrode 122d by injecting the second access nmos pass transistor Ta2 that n-type dopant forms and the drain electrode 142d of the second driving N MOS transistor Td2 are connected with the drain electrode 162d of the 2nd p-channel thin-film transistor Tf2 by the formation of injection p-type dopant, and are connected with 190c by contact site 190a, 190b with the grid 130 of the first driving N MOS transistor Td1 and the grid 150 of a p-channel thin-film transistor Tf1.
And the source electrode 152s of a p-channel thin-film transistor Tf1 of injection p-type dopant and the source electrode 162s of the 2nd p-channel thin-film transistor Tf2 are connected to power supply potential layer Vcc by contact site 154 and 164 respectively.Power supply potential layer Vcc roughly is positioned at the centre of active area 102.And the grid 140 of the grid 130 of the first driving N MOS transistor Td1 and the second driving N MOS transistor Td2 is arranged in parallel within on the opposite side of power supply potential layer Vcc.And insulating barrier 210 is held between power supply potential layer Vcc and grid 130 and the grid 140.
With reference to Fig. 2 B, earth potential layer Vss passes the below that another insulating barrier 200 is formed on power supply potential layer Vcc.Earth potential layer Vss forms buried layer BN+, and it forms by injecting n-type dopant at active area 102.And earth potential layer Vss is as the common-source of the first driving N MOS transistor Td1 and the second driving N MOS transistor Td2, and wherein the first driving N MOS transistor Td1 and the second driving N MOS transistor Td2 are formed on the opposite side of power supply potential layer Vcc.
In above-mentioned SRAM, earth potential layer Vss activates by the highfield that is formed at power supply potential layer Vcc.And, when local equipotential layer Vss is activated, produce the effect of the channel length shortening that makes the first driving N MOS transistor Td1 and the second driving N MOS transistor Td2.Therefore, can improve the speed of service of this SRAM.
Simultaneously, shown in Fig. 2 B, for fear of latch phenomenon occurring when power supply potential layer Vcc and the earth potential layer Vss short circuit, insulating barrier 200 is formed between power supply potential layer Vcc and the earth potential layer Vss.Especially, the opposite end of insulating barrier 200 forms the beak shape, thereby has biconvex shape.
Hereinafter, with 3A, Fig. 3 B and Fig. 3 C describe the method that forms power supply potential layer Vcc and earth potential layer Vss with said structure with reference to the accompanying drawings.
At first, as shown in Figure 3A, on substrate 100, form photoresist pattern 204 with the opening that roughly passes this active area center.With using photoresist pattern 204 to inject the substrate that n-type dopant I exposes as mask, therefore form BN+ (buried N+) diffusion zone, this zone will be as earth potential layer Vss.At this moment, because the end face of substrate is opened, the injection of ion allows recess 202 to be formed on the end face that exposes substrate.
Then, shown in Fig. 3 B, remove photoresist pattern 204 fully, then, remove the end face of substrate fully.The oxide layer that forms by oxidation since recess 202 and the dopant that injects on earth potential layer Vss, expand.In other words, the opposite end that is formed on the insulating barrier 200 on the earth potential layer Vss forms the beak shape, thereby has biconvex shape.
Another oxide layer 200a can be formed on the residue place of not injecting dopant in the active area.Shown in Fig. 3 C, oxide layer 200a is removed fully by follow-up technology.The conductive layer of doped polysilicon layer or use tungsten is formed on the insulating barrier 200, forms power supply potential layer Vcc thus.Like this, power supply potential layer Vcc and earth potential layer Vss by insulating barrier 200 separately can avoid latch phenomenon effectively.
In SRAM of the present invention, power supply potential layer and earth potential layer are set parallel to each other.Like this, the earth potential layer is activated by the highfield that the power supply potential layer produces.The activation of earth potential layer has improved the speed of service of described driving N MOS transistor.As a result, the speed of service of SRAM is greatly improved.And, use and be formed on biconvex insulating barrier between power supply potential layer close to each other and the earth potential layer, can avoid latch phenomenon effectively.
And according to the present invention, described driving N MOS transistor point symmetry ground each other forms.This point is applied to the access nmos pass transistor too.Like this, can keep the symmetry of sram cell, to improve the stability of SRAM.
In addition, the grid 110 and 120 of described driving N MOS transistor Td1 and Td2 forms vertically, thus, and the area minimum that on the plane of substrate, occupies.As a result, also improved the integrated level of sram cell.
Those skilled in the art should be understood that and can carry out multiple modification and remodeling to the present invention.Therefore, be intended to illustrate that the modification and the remodeling that fall into appended claims book and its equivalency range that is provided is provided in the present invention.

Claims (9)

1. static random access memory, it comprises: first access transistor and second access transistor that are made of metal oxide semiconductor transistor; First driving transistors and second driving transistors that constitute by metal oxide semiconductor transistor; And the p-channel thin-film transistor and the 2nd p-channel thin-film transistor that are used as pull-up device, described static random access memory also comprises:
The earth potential layer, it is provided as the common-source of this first driving transistors and this second driving transistors, and forms by dopant is injected Semiconductor substrate;
The power supply potential layer is connected with the source electrode of a p-channel thin-film transistor and the 2nd p-channel thin-film transistor, and is provided with near this earth potential layer; And
Insulating barrier is formed on this substrate, and between this earth potential layer and this power supply potential layer.
2. static random access memory as claimed in claim 1, wherein, this earth potential layer and this power supply potential layer are provided with in parallel with each other.
3. static random access memory as claimed in claim 1, wherein, this insulating barrier is the oxide layer that forms by this substrate of oxidation.
4. static random access memory as claimed in claim 3, wherein, this oxide layer forms biconvex shape.
5. static random access memory as claimed in claim 1, wherein, this first driving transistors and this second driving transistors have the grid on the opposite side that is oppositely arranged on this power supply potential layer.
6. method of making static random access memory, wherein, this static random access memory comprises: first access transistor and second access transistor that are made of metal oxide semiconductor transistor; First driving transistors and second driving transistors that constitute by metal oxide semiconductor transistor; And the p-channel thin-film transistor and the 2nd p-channel thin-film transistor that are used as pull-up device, this method may further comprise the steps:
Form the photoresist pattern that exposes active area of semiconductor substrate with preset width;
Dopant is injected the part that this active area is exposed by this photoresist pattern, to form the earth potential layer thus;
Remove this photoresist pattern;
On this earth potential layer, form insulating barrier;
On this insulating barrier, form the power supply potential layer.
7. method as claimed in claim 6, wherein, the step that forms insulating barrier may further comprise the steps:
This substrate of oxidation is to form oxide layer; And
Remove the remaining oxide layer outside this oxide layer that is formed on this earth potential layer.
8. method as claimed in claim 7, wherein, this oxide layer that is formed on this earth potential layer forms biconvex shape.
9. method as claimed in claim 6, wherein, this earth potential layer and this power supply potential layer are formed parallel to each other.
CNB200610170188XA 2005-12-29 2006-12-25 Static random access memory and manufacture method thereof Expired - Fee Related CN100573877C (en)

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KR1020050134466A KR100660277B1 (en) 2005-12-29 2005-12-29 Sram device and manufacturing method thereof

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CN100573877C true CN100573877C (en) 2009-12-23

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JP5561897B2 (en) 2007-07-13 2014-07-30 富士通株式会社 Measuring method, measuring apparatus and measuring program
US7773424B2 (en) * 2008-05-23 2010-08-10 Freescale Semiconductor, Inc. Circuit for and an electronic device including a nonvolatile memory cell and a process of forming the electronic device
US9059032B2 (en) * 2011-04-29 2015-06-16 Texas Instruments Incorporated SRAM cell parameter optimization
CN103247628B (en) * 2012-02-06 2016-06-15 无锡华润上华半导体有限公司 SRAM device and manufacture method thereof

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JP2749087B2 (en) * 1988-12-26 1998-05-13 株式会社日立製作所 Semiconductor integrated circuit device
JP2927463B2 (en) * 1989-09-28 1999-07-28 株式会社日立製作所 Semiconductor storage device
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JPH0770624B2 (en) * 1990-06-22 1995-07-31 株式会社東芝 Semiconductor integrated circuit
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US8134213B2 (en) 2012-03-13
KR100660277B1 (en) 2006-12-20
CN1992281A (en) 2007-07-04
JP2007184579A (en) 2007-07-19
DE102006061028A1 (en) 2007-07-26
JP4648296B2 (en) 2011-03-09
US20070158758A1 (en) 2007-07-12

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